That could be why. The images on the Amazon.jp links are all new decos with shiny paints.
I'd expect actual store retail prices to vary (and discount later), but I was just going by the Amazon.jp prices, which had TFPrime (Arms Micron) Deluxe toys for 2000yen over the last year, but are listing the Generations Deluxe toys for 3000yen... a significant enough increase to note it as a being applicable to that new line. And judging by the paint-work, it explains why these ones are so much more expensive.